Laboratoire Analyse et Modélisation pour la Biologie et l'Environnement, Université d'Evry Val d'Essonn e, Bâtiment Maupertuis, Boulevard François Mitterrand, 91025 Evry, France.
Inorg Chem. 2011 Aug 15;50(16):7769-78. doi: 10.1021/ic200918q. Epub 2011 Jul 11.
The structure of the Pb(UMP)-H (UMP = uridine-5'-monophosphate) complex was studied in the gas phase by combining electrospray ionization (ESI), tandem mass spectrometry, and mid-infrared multiple photon dissociation (IRMPD) spectroscopy. The results obtained show that Pb(2+) ions interact not only with the deprotonated phosphate group but also with a carbonyl group of the nucleobase moiety by folding of the mononucleotide, resulting in macrochelates that are not likely to be present in solution. Comparison between the IRMPD and DFT-computed spectra suggests that the ESI-generated complex likely corresponds to a mixture of several structures, and establishes the enolic tautomers as the most abundant species for the Pb(UMP)-H ion, while the very weak IRMPD signal observed at ∼1763 cm(-1) points to a minor population of oxo forms. Our data also suggest that losing the nucleobase residue under CID conditions does not necessarily mean a lack of interaction between the metal and the nucleobase moiety, as commonly reported in the literature for large oligonucleotides.
通过结合电喷雾电离（ESI）、串联质谱和中红外多光子解离（IRMPD）光谱，研究了Pb(UMP)-H（UMP = 尿苷-5'-单磷酸）配合物在气相中的结构。结果表明，Pb(2+)离子不仅与去质子化的磷酸基团相互作用，而且通过单核苷酸的折叠与碱基部分的一个羰基相互作用，导致大环配合物不太可能存在于溶液中。IRMPD 和 DFT 计算光谱的比较表明，ESI 产生的配合物可能对应于几种结构的混合物，并确定烯醇互变异构体为Pb(UMP)-H离子最丰富的物种，而在约 1763 cm(-1)处观察到的非常弱的 IRMPD 信号表明存在较少的氧形式。我们的数据还表明，在 CID 条件下失去碱基残基并不一定意味着金属与碱基部分之间缺乏相互作用，这与文献中通常报道的大寡核苷酸情况不同。
